1. Field of the invention
The invention concerns a system and a method of communication between circuit mode communication installation core units interconnected by point-to-point circuits.
2. Description of the Prior Art
French patent application 9009442 describes an interconnect network which functions as a core component of a digital communication installation, an integrated services type installation, for example, in which the units of the interconnecting network are interconnected by point-to-point circuits adapted to their specific requirements.
An interconnect network of this kind comprises, for example, a subnetwork of digital installation core units supporting circuit mode, i.e. units operating directly or indirectly in the core during synchronous time-division switching of data successively transferred in the form of binary blocks (frames) of the same size, a block routinely comprising one byte and the transfer period being 125 .mu.s in the conventional case of 64 kbit/s circuit switching.
This enables the transfer of structured information at 8 kHz, including speech or other audio frequency signals sampled and encoded in the form of bytes and data also in the form of bytes.
The units concerned are usually the various telephone type units, their control units and possibly associated auxiliary units (known as service circuits).
The telephone units are, for example, of the analog telephone interface controller type (CCITT S0/T0 or S2/T2 level, or a chosen specific level).
The invention therefore proposes a system of communication between circuit mode core units interconnected by point-to-point circuits of a communication installation comprising at most "n" units.